Snap one point copy (SnapOPC) is known as one of backup techniques of a backup target volume in the field of storage products. SnapOPC is to produce a snapshot, i.e., data on the backup target volume at a given time (containing no update subsequent to the given time). More specifically, SnapOPC is a technique of backing up only data prior to an updating process at a location where the updating process is performed (as disclosed in Japanese Laid-open Patent Publication No. 2007-172082).
The above-described known technique cannot learn whether bad data (data unreadable) has a backup.
More specifically, SnapOPC stores only pre-update data at a location having undergone an update process instead of storing all the data on a backup target volume at a given time. In accordance with SnapOPC, bad data is not necessarily backed up. To learn whether the bad data is backed up or not, an engineer having provided service to storage products needs to be accessed for inquiry.